SSL Labs requires a public IP address. So, I've used a service called ngrok to tunnel requests from a public IP address to my localhost and then scan the ngrok provided sub-domain. This works for checking the configuration, but not the authentication, as the certificate provided to SSL Labs is the ngrok wildcard instead of your local server's certificate. Also, ngrok appears to only tunnel TLS traffic and not SSL, so if your local server accepts SSLv2 or SSLv3 connections, it will not be tunneled and it will not be reported in the SSL Labs report. Otherwise, it will report the right TLS protocols, cipher suites, handshake simulation, and protocol details from your local server.

According the the ngrok docs, there is a way to configure it to serve up your certificate, but in my testing this did not work. SSL Labs always reported the ngrok wildcard certificate.

Alternatively, you don't have to use SSL Labs. You can download and run a bash script called cipherscan to get a more limited report on the SSL cipher suites that are supported by your local server.